Resistor for high voltage



2 Sheets-Sheet 1 BLW290125 H. FoRwALD ETAL RESISTOR FOR HIGH VOLTAGE z ra- Z Amm wml

Feb. 14, 1967 v Filed March 2, 1965 Feb. 14, 1967 H. lFQRWALD ETAL RESISTOR FOR HIGH VOLTAGE Filed March 2, 1965 2 Sheets-Sheet 2 United States Patent O 3,304,529 RESISTR FR HIGH VLTAGE Haakon Forwald, Lauri Savolainen, and Samuel Berg,

Ludvika, Sweden, assignors to Allmanna Svenska Elektriska Aktieholaget, Vasteras, Sweden, a corporation of Sweden Filed Mar. 2, 1965, Ser. No. 436,532 Claims priority, application Sweden, Mar. 12, 1964,

3,064/64; Ian. 27, 1965, 1,030/65 Claims. (Cl. S33-21) This invention relates to a resistor construction, and more specifically relates to a damping resistor for use with high voltage circuit breakers.

Resistors are commonly connected in parallel with the main interrupting gap of a high voltage circuit breaker in order to control the recovery voltage appearing across the high voltage circuit breaker contacts when these contacts separate. Thus, these resistors are exposed to extremely high impulse currents for a very short time.

The loading time of these resistors is so short that substantially all ot the energy is stored as heat in the resistor body which thereafter is slowly cooled. Thus, the overall size of the resistor is relatively large, since for a given power and given loading time, the temperature to which the resistor material is heated is inversely proportional to the weight of the resistor material. As a resistor is made lighter and smaller, the temeprature to which it rises during operation is increased to some limiting factor dependent upon the thermal capability of the insulation material.

Another limitation on the design of such resitscrs is that a relatively long length is required because of the relatively long resistor wire lengths required 'within a comparatively reasonable overall length while still retaining reliable insulation levels between the resistor windings.

The principle of the present invention is to prov-ide a novel construction for damping resistors for use with high voltage circuit breakers which provides an extremely high concentration of resistor material along with high electrical strength, whereby a relatively large resistor rnass having suitable eiective long length is provided giving the device high thermal inertia and compactness. In addition, the novel invention provides a simplied method for the manufacture and assembly of such resistors.

Thus, with the invention, and while a relatively small resistor volume is used, the temperature rise is low so that conventional insulation methods and materials can be used.

In accordance with the invention, the resistor is formed of a plurality of disk coils (spirally wound discs) having a generally con-ical shape which are separated from one another by conically arranged insulation disks. The adjacent coils are then alternately connected to one another at their interiors and at their exteriors.

Upon the -occurrence of certain special types of faults in high voltage networks, for example when a short circuit occurs at a distance of a few kilometres from a breaker, the recovery voltage across the breaker terminals after the breaking can have a frequency of some tens of kilocycles. If the resistor is to function effectively at these relatively high frequencies it is particularly important that it has a small inductance.

A resistor with a particularly small inductance can be obtained by making the coils substantially alike and arranging them in the staple with the windings in the same direction. As the current in every other coil is conducted from the inner layer to the outer layer and in the alternate coils from the outer to the inner layer, the magnetic fields generated by adjacent coils will be in opposing directions, thereby resulting in a comparatively low inductance.

A considerably greater decrease in the inductance of the resistor can, however, be reached by forming each resistor winding of vseveral partial conductors lying beside each other, so-called partial discs, so that the adjoining partial discs have opposite winding directions. In each resistor winding there would suitably be an even number of partial discs.

All the initial ends of the partial conductors in a resistor winding are connected suitably to a common inner contact ring, which for every other resistor winding is provided with axially projecting resilient tongues which 'are intended to tit in a bush-like inner contact ring belonging to an adjoining resistor winding. The inner galvanic connection between adjacent windings can thereby `be made in a particularly simple way.

Accordingly, a primary object of this invention is to provide a high voltage resistor structure formed of spirally wound disks of resistance wire.

Another object of this linvention is to provide a novel damping resistor for high voltage circuit breakers which provides a relatively low temperature rise with a relatively small resistor volume.

Another object of this invention is to provide a novel alternating arrangement of insulation disks and spirally wound resistance wire disks for the formation of a resistor having high thermal inertia.

Another object of this invention is to provide a novel damping resistor with a particularly small inductance.

These and other objects of this invention will become apparent from the following description when taken in connection with the drawings, in which:

FIGURE l is a cross-sectional view of a resistor constructed in accordance with the invention.

FIGURE 2 is a partial, exploded view in cross-section of the arrangement of FIGURE l.

FIGURE 3 is a top view of FIGURE l.

FIGURE 4 is a partial, top plan View of a section of the resistance winding of FIGURES l and 2.

FIGURE 5 is a central, cross-sectional view of a resistor coil composed of four disk elements.

FIGURE 6 shows a larger scale the right part of the coil according to FIGURE 5 with the current directions indicated.

FIGURE 7 is a cross-sectional View of a resistor coil similar to FIGURE 5, but having only two disk elements.

Referring now to FIGURE 1, the resistor illustrated therein is formed of a plurality of identically spirally wound coils of a suitable resistance wire, illustrated as coils 10 to 23. Each of coils 10 to 23 are identical to one another, and are formed to be slightly conical or dished to define alternate pairs of disks which are dished inwardly toward one another.

The interior ends of alternating pairs of disks are then connected to one another, as illustrated by t-he arrow 24 in FIGURE 2 for the case of conical spirals 10 and 11. In a similar manner, the terminating interior ends of coil pairs lit-13, 11i-l5, 16-17, '1S-19, 20-21 and 22-23 are connected together.

The exterior ends of adjacent spirals are similarly connected together, as illustrated in FIGURE 2 by the line 25, the terminating ends of disks 11-12, 13-14, 546, 1748, 19-20 and 21-22 being similarly electrically connected together. The terminals of the device are then defined by the outer terminating ends of disks Iii and 23.

Each of the spiral resistance windings 10 to 23 are formed of a plurality of turns and are of identical construction. In order to insulate between adjacent turns, the resistance wire may be coated with a suitable enamel insulation in the standard manner, or, for higher ternperatures, can be coated with a silicon lacquer or can have interposed between adjacent turns a glass fiber insulation strip. Thus, in FIGURE 4, a continuous strip 26 of glass fiber can be interposed between the continuous strip 27 of insulation wire deiining, for example, a portion of the winding 10.

In order to support the various 'windings 10 to 23, the novel arrangement is used of outwardly tlared insulation disks 28 to 34- and inwardly flared alternate disks 35 to 40. The disks 28 to 40 may be of any suitable insulation material, and could, for example, be machined ber bodies or cast epoxy bodies.

The complete stack -is then held together by means of two end insulation disks 41 and 42 which are outwardly dished to cooperate with the inwardly dished shape of 'windings 10 and 23.

A central insulation rod 43 is then secured to the end insulation members 41 and 42 in any desired manner as by being directly secured to one disk and threadably secured to the other disk so as to clamp the complete assembly together.

In FIGURE a resistor coil is shown in which the resistor material is wound so that a slightly conical resistor winding 51 is formed. The resistor winding 51 is wound of four insulated partial conductors, which form four disk elements 52 to 55. Adjacent disk elements, for example 52 and 53, have opposite winding directions and all the initial ends of the disk elements 52 to 55 in the resistor winding 51 are connected to a common inner contact ring 56 and all the linal ends t0 an outer outlet ring 57. From FIGURE 6 the current direction in the disk elements is evident. The crosses and points represent that the current enters and comes out of the plane of the paper.

The inner contact ring 56 is provided with a number of axially projecting resilient tongues 58, Iwhich are intended to lit in a bush-like inner contact ring 59 of the type shown in FIGURE 7. Besides, this ligure shows a resistor winding 60 of a similar type to that shown in FIGURE 5, but with only two disk elements 61 and 62.

The different disk elements in a resistor winding have equal numbers of winding t-urns and consequently have equal resistance values, so that the total current through the winding is divided into similarly large partial currents in each partial conductor. A winding manufactured in this 'way has particularly low inductance and the proposed arrangement produces `the further advantage that the skin effect is of less importance. The inductance as well as the skin eliect decreases with the increased number of partial conductors.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein but only by the appended claims. I

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. A high voltage resistor comprising, in combination: a plurality of coaxial spirally wound windings of resistor wire wound in the same direction, means supporting said windings in spaced relation to each other, said resistor windings having internal wire end portions and external wire end portions at the interior and. exterior of their said windings; first alternate pairs of adjacent resistor windings having their said internal wire end portions electrically connected to one another, second alternate pairs of adjacent resistor windings having their said external wire end portions electrically connected to one another; alternate adjacent pairs of said resistor windings being dished toward and away from one another, respectively, said supporting means comprising a plurality of radially tapering coaxial insulation discs each interposed between and lling the spaces between respective adjacent windings of said spaced resistor windings.

2. In a resistance as claimed in claim 1, a first and second end insulation disc positioned at opposite ends of said resistor, and a central clamping shaft of insulating material extending between and secured to said lirst and second end insulation discs; said plurality of resistor windings and said plurality of said insulation discs having aligned central openings therein; said central clamping shaft extending through said aligned openings and forcing said end insulation discs toward one another to clamp said resistor windings and insulation discs together.

3. In a resistance as claimed in claim 1, each of said resistor windings including an insulation tape interposed between adjacent convolutions of said winding.

4. In a resistance as claimed in claim 1, each resistor winding comprising a plurality of adjacent partial conductors, said adjacent partial conductors being alternately wound in opposite directions.

5. In a resistance as claimed in claim 4, an inner contact ring having axially projecting contact tongues; said contact tongues maintaining electrical contact between the inner ends of said rst alternate pairs of adjacent resistor windings, all said partial conductors of each said resistor winding being connected to said common inner contact ring.

References Cited by the Examiner UNITED STATES PATENTS 1,275,151 8/1918 Green 317--61.5 1,816,838 8/1931 Gay 317-61.5 1,887,461 11/1932 Norris 317-615 X 2,233,939 3/1941 Miller S17-61.5 X 3,096,496 7/1963 Burrage et al. 338-21 3,227,983 1/1966 Braun 338-21 RICHARD M. WOOD, Primary Examiner.

W. D. BROOKS, Assistant Examiner. 

1. A HIGH VOLTAGE RESISTOR COMPRISING, IN COMBINATION: A PLURALITY OF COAXIAL SPIRALLY WOUND WINDINGS OF RESISTOR WIRE WOUND IN THE SAME DIRECTION, MEANS SUPPORTING SAID WINDINGS IN SPACED RELATION TO EACH OTHER, SAID RESISTOR WINDINGS HAVING INTERNAL WIRE END PORTIONS AND EXTERNAL WIRE END PORTIONS AT THE INTERIOR AND EXTERIOR OF THEIR SAID WINDINGS; FIRST ALTERNATE PAIRS OF ADJACENT RESISTOR WINDINGS HAVING THEIR SAID INTERNAL WIRE END PORTIONS ELECTRICALLY CONNECTED TO ONE ANOTHER, SECOND ALTERNATE PAIRS OF ADJACENT RESISTOR WINDINGS HAVING THEIR SAID EXTERNAL WIRE END PORTIONS ELECTRICALLY CONNECTED TO ONE ANOTHER; ALTERNATE ADJACENT PAIRS OF SAID RESISTOR WINDINGS BEING DISHED TOWARD AND AWAY FROM ONE ANOTHER, RESPECTIVELY, SAID SUPPORTING MEANS COMPRISING A PLURALITY OF RADIALLY TAPERING COAXIAL INSULATION DISCS EACH INTERPOSED BETWEEN AND FILLING THE SPACES BETWEEN RESPECTIVE ADJACENT WINDINGS OF SAID SPACED RESISTOR WINDINGS. 